The present invention relates generally to communications devices for the handicapped, and more specifically to an improved scanning process for use with lists and matrices.
Many attempts have been made to enable persons with motor and/or speech impairments to communicate more effectively with others. Methods presently in use generally employ one or more electrical switches coupled to an electronic control circuit. Closure of these switches by the user allows desired symbols or preselected phrases to be chosen and communicated to others. Typically, a keyboard of some type is coupled through control logic to a printer or lighted display.
Keyboards of any type have serious drawbacks in that they are not suitable for use by many handicapped or impaired persons. Although these persons may have good cognitive faculties, due to various physical impairments they are not able to accurately select and close the contacts on a keyboard matrix.
One alternative to the matrixed keyboard input is the use of a single switch, coupled with a dynamic presentation of the items to be selected. For example, a row or matrix of lights corresponding to letters of the alphabet or preselected messages can be individually, sequentially lighted. The user is then able to make his selection by closing the single switch while the desired item is being presented. This method has advantages in that it is inherently very simple to use and understand by anyone who is able to manipulate a single switch.
However, such a method has a serious drawback in that selection of individual items can be extremely time consuming. Each item must be presented for a long enough time period to insure that the user will be able to comprehend that his desired item is being presented, and make the necessary switch closure. For most impaired persons, such a period runs several seconds, and may run several tens of seconds for some. If an item must be selected from a group or list of forty or more elements, it is easily seen that the element selection process may take several minutes. This is especially true when the user's attention wanders, causing him to miss the desired selection and requiring him to wait for the scanning process to return. This wandering of attention is an important problem, and is greatly exaggerated by the fact that the user must wait a long time for his selected element to be presented. Long delays cause boredom and frustration, and may sharply curtail the use of an otherwise helpful communication aid.
It would be desirable to provide a communications method and device which utilizes a dynamic scanning presentation of elements for selection by the user. It is further desirable that the element selection can be made by operating a single switch, and it is extremely desirable that the average selection time and quantity of switch operations per selection is kept to a minimum.
Therefore, according to the present invention, a method for dynamic scanning of lists or arrays comprises the steps of scanning through the list in a forward direction at a speed greater than the response time of the user, and, upon receipt of a switch closure, reversing direction and scanning at a slow speed, thereby allowing item selection upon a second switch closure by the user. The forward and reverse scanning speeds are preferably dependent on parameters established by the response abilities of the user.
It is preferable that a device constructed according to the present invention be able to interface with a variety of communications devices. Therefore, the present invention provides a general apparatus for providing the scanning and interpreting of switch closures, and allowing interfacing with a communications device to be selected by the user. Thus, modifications of the device disclosed in connection with the drawings can be used to interface the impaired user with a variety of electronic and microprocessor driven displays and devices.